Gyro sensor calibration method

Abstract

In a method of calibrating a gyro sensor mounted on a vehicle for measuring an angular velocity in a rotating direction generated about an axis of a vertical direction, a lateral shift amount detection process of detecting lateral shift amounts of the vehicle with respect to magnetic markers laid in a road, an azimuth estimation process of estimating, when the vehicle passes over a laying location where two magnetic markers are laid, an azimuth of the vehicle by a calculation process with the lateral shift amounts with respect to the two magnetic markers taken as input values, and a calibration process of calibrating the gyro sensor by using the azimuth of the vehicle estimated by the azimuth estimation process, are performed.

The invention claimed is: 
     
       1. A gyro sensor calibration method in a vehicle including a gyro sensor which measures an angular velocity in a rotating direction generated about an axis of a vertical direction, the method comprising:
 a lateral shift amount detection process of detecting lateral shift amounts of the vehicle with respect to magnetic markers laid in a road; an azimuth estimation process of estimating, when the vehicle passes over a laying location where at least two of the magnetic markers are laid, 
 an azimuth of the vehicle by a calculation process with the lateral shift amounts detected by the lateral shift amount detection process for the at least two of the magnetic markers taken as input values; 
 a calibration process of calibrating the gyro sensor by using the azimuth of the vehicle estimated by the azimuth estimation process; and 
 an integration process of temporally integrating measurement values of the gyro sensor while the vehicle passes over two of the laying locations, the two of the laying locations being separate and along the road, and wherein at least two of the magnetic markers are laid at each of the two of the laying locations, wherein 
 in the calibration process, the gyro sensor is calibrated so that a difference between a vehicle rotation angle, which is a difference in azimuths of the vehicle estimated by the azimuth estimation process at each of the two of the laying locations, and a measured rotation angle, which is an integrated value by the integration process, gets smaller than before performing the calibration process. 
 
     
     
       2. A gyro sensor calibration method in a vehicle including a gyro sensor which measures an angular velocity in a rotating direction generated about an axis of a vertical direction, the method comprising:
 a lateral shift amount detection process of detecting lateral shift amounts of the vehicle with respect to magnetic markers laid in a road; 
 an azimuth estimation process of estimating, when the vehicle passes over a laying location where at least two of the magnetic markers are laid, an azimuth of the vehicle by a calculation process with the lateral shift amounts detected by the lateral shift amount detection process for the at least two of the magnetic markers taken as input values; and 
 a calibration process of calibrating the gyro sensor by using the azimuth of the vehicle estimated by the azimuth estimation process, 
 wherein the calibration process is a process in which, when the vehicle passes over the laying location, the laying location being provided on a linear road, when a differential value between said lateral shift amounts is equal to or smaller than a predetermined value, a value of the angular velocity measured by the gyro sensor is brought closer to zero. 
 
     
     
       3. The gyro sensor calibration method according to  claim 1 , wherein an information providing part is annexed to at least one of the magnetic markers arranged in the laying location, and the information providing part provides marker azimuth information identifying a direction of a line segment connecting the at least two of the magnetic markers arranged in the laying location. 
     
     
       4. The gyro sensor calibration method according to  claim 3 , wherein the information providing part is a wireless tag attached to the at least one of the magnetic markers. 
     
     
       5. The gyro sensor calibration method according to  claim 1 , wherein an information providing part is annexed to at least one of the magnetic markers arranged in the laying location, and the information providing part provides marker azimuth information identifying a direction of a line segment connecting the at least two of the magnetic markers arranged in the laying location. 
     
     
       6. The gyro sensor calibration method according to  claim 5 , wherein the information providing part is a wireless tag attached to the at least one of the magnetic markers. 
     
     
       7. The gyro sensor calibration method according to  claim 2 , wherein an information providing part is annexed to at least one of the magnetic markers arranged in the laying location, and the information providing part provides marker azimuth information identifying a direction of a line segment connecting the at least two of the magnetic markers arranged in the laying location. 
     
     
       8. The gyro sensor calibration method according to  claim 7 , wherein the information providing part is a wireless tag attached to the at least one of the magnetic markers. 
     
     
       9. The gyro sensor calibration method according to  claim 1 , wherein in the calibration process, the gyro sensor is calibrated so that the difference between the vehicle rotation angle and the measured rotation angle becomes zero. 
     
     
       10. The gyro sensor calibration method according to  claim 3 , wherein the marker azimuth information indicates the direction of the line segment connecting the at least two of the magnetic markers arranged in the laying location. 
     
     
       11. The gyro sensor calibration method according to  claim 7 , wherein the marker azimuth information indicates the direction of the line segment connecting the at least two of the magnetic markers arranged in the laying location.